2 * Networking abstraction in PuTTY.
4 * The way this works is: a back end can choose to open any number
5 * of sockets - including zero, which might be necessary in some.
6 * It can register a bunch of callbacks (most notably for when
7 * data is received) for each socket, and it can call the networking
8 * abstraction to send data without having to worry about blocking.
9 * The stuff behind the abstraction takes care of selects and
10 * nonblocking writes and all that sort of painful gubbins.
13 #ifndef PUTTY_NETWORK_H
14 #define PUTTY_NETWORK_H
16 typedef struct SockAddr_tag
*SockAddr
;
17 /* pay attention to levels of indirection */
18 typedef struct socket_function_table
**Socket
;
19 typedef struct plug_function_table
**Plug
;
21 struct socket_function_table
{
22 Plug(*plug
) (Socket s
, Plug p
);
23 /* use a different plug (return the old one) */
24 /* if p is NULL, it doesn't change the plug */
25 /* but it does return the one it's using */
26 void (*close
) (Socket s
);
27 int (*write
) (Socket s
, char *data
, int len
);
28 int (*write_oob
) (Socket s
, char *data
, int len
);
29 void (*flush
) (Socket s
);
30 /* ignored by tcp, but vital for ssl */
31 char *(*socket_error
) (Socket s
);
34 struct plug_function_table
{
36 (Plug p
, char *error_msg
, int error_code
, int calling_back
);
37 /* error_msg is NULL iff it is not an error (ie it closed normally) */
38 /* calling_back != 0 iff there is a Plug function */
39 /* currently running (would cure the fixme in try_send()) */
40 int (*receive
) (Plug p
, int urgent
, char *data
, int len
);
42 * - urgent==0. `data' points to `len' bytes of perfectly
45 * - urgent==1. `data' points to `len' bytes of data,
46 * which were read from before an Urgent pointer.
48 * - urgent==2. `data' points to `len' bytes of data,
49 * the first of which was the one at the Urgent mark.
51 void (*sent
) (Plug p
, int bufsize
);
53 * The `sent' function is called when the pending send backlog
54 * on a socket is cleared or partially cleared. The new backlog
55 * size is passed in the `bufsize' parameter.
57 int (*accepting
)(Plug p
, void *sock
);
59 * returns 0 if the host at address addr is a valid host for connecting or error
64 void sk_init(void); /* called once at program startup */
65 void sk_cleanup(void); /* called just before program exit */
67 SockAddr
sk_namelookup(char *host
, char **canonicalname
);
68 void sk_getaddr(SockAddr addr
, char *buf
, int buflen
);
69 void sk_addr_free(SockAddr addr
);
71 Socket
sk_new(SockAddr addr
, int port
, int privport
, int oobinline
,
74 Socket
sk_newlistener(int port
, Plug plug
, int local_host_only
);
76 Socket
sk_register(void *sock
, Plug plug
);
78 #define sk_plug(s,p) (((*s)->plug) (s, p))
79 #define sk_close(s) (((*s)->close) (s))
80 #define sk_write(s,buf,len) (((*s)->write) (s, buf, len))
81 #define sk_write_oob(s,buf,len) (((*s)->write_oob) (s, buf, len))
82 #define sk_flush(s) (((*s)->flush) (s))
84 #ifdef DEFINE_PLUG_METHOD_MACROS
85 #define plug_closing(p,msg,code,callback) (((*p)->closing) (p, msg, code, callback))
86 #define plug_receive(p,urgent,buf,len) (((*p)->receive) (p, urgent, buf, len))
87 #define plug_sent(p,bufsize) (((*p)->sent) (p, bufsize))
88 #define plug_accepting(p, sock) (((*p)->accepting)(p, sock))
92 * Each socket abstraction contains a `void *' private field in
93 * which the client can keep state.
95 * This is perhaps unnecessary now that we have the notion of a plug,
96 * but there is some existing code that uses it, so it stays.
98 void sk_set_private_ptr(Socket s
, void *ptr
);
99 void *sk_get_private_ptr(Socket s
);
102 * Special error values are returned from sk_namelookup and sk_new
103 * if there's a problem. These functions extract an error message,
104 * or return NULL if there's no problem.
106 char *sk_addr_error(SockAddr addr
);
107 #define sk_socket_error(s) (((*s)->socket_error) (s))
110 * Set the `frozen' flag on a socket. A frozen socket is one in
111 * which all READABLE notifications are ignored, so that data is
112 * not accepted from the peer until the socket is unfrozen. This
113 * exists for two purposes:
115 * - Port forwarding: when a local listening port receives a
116 * connection, we do not want to receive data from the new
117 * socket until we have somewhere to send it. Hence, we freeze
118 * the socket until its associated SSH channel is ready; then we
119 * unfreeze it and pending data is delivered.
121 * - Socket buffering: if an SSH channel (or the whole connection)
122 * backs up or presents a zero window, we must freeze the
123 * associated local socket in order to avoid unbounded buffer
126 void sk_set_frozen(Socket sock
, int is_frozen
);
129 * Call this after an operation that might have tried to send on a
130 * socket, to clean up any pending network errors.
132 void net_pending_errors(void);
134 /********** SSL stuff **********/
137 * This section is subject to change, but you get the general idea
138 * of what it will eventually look like.
141 typedef struct certificate
*Certificate
;
142 typedef struct our_certificate
*Our_Certificate
;
143 /* to be defined somewhere else, somehow */
145 typedef struct ssl_client_socket_function_table
**SSL_Client_Socket
;
146 typedef struct ssl_client_plug_function_table
**SSL_Client_Plug
;
148 struct ssl_client_socket_function_table
{
149 struct socket_function_table base
;
150 void (*renegotiate
) (SSL_Client_Socket s
);
151 /* renegotiate the cipher spec */
154 struct ssl_client_plug_function_table
{
155 struct plug_function_table base
;
156 int (*refuse_cert
) (SSL_Client_Plug p
, Certificate cert
[]);
157 /* do we accept this certificate chain? If not, why not? */
158 /* cert[0] is the server's certificate, cert[] is NULL-terminated */
159 /* the last certificate may or may not be the root certificate */
160 Our_Certificate(*client_cert
) (SSL_Client_Plug p
);
161 /* the server wants us to identify ourselves */
162 /* may return NULL if we want anonymity */
165 SSL_Client_Socket
sk_ssl_client_over(Socket s
, /* pre-existing (tcp) connection */
168 #define sk_renegotiate(s) (((*s)->renegotiate) (s))